Air-cooling apparatus



Jan. 11 1927. A. R. SMITH AIR 000mm APPARATUS Filed June 6. 1925Inventor Arthur" R. SmLth W H La Attorngy Patented Jan. 11, 1927.

UNITED STATES PATENT OFFICE.

ARTHUR R. SMITH, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW, YORK.

AIR-COOLING APPARATUS.

Application filed June 6, 1925. Serial No. 35,400.

The present invention relates toair cooling apparatus, such as surfaceair coolers and air cooling sections of surface condensers, and moreparticularly it relates to the cooling tubes used in such apparatus,which, as is well understood, are usually mounted in groups or banksbetween common supporting headers or tube sheets, and which must beindividually removable in case of leakage or other fault withoutdisturbing other tubes in the bank.

The use of finned tubes in air cooling paratus of the type abovementioned has well recognized advantages, but has heretofore carriedwith it the disadvantage that in order to permit the removal of a faultytube from a tube sheet carrying other tubes, removable thimbles orpacking rings were required about the tube joint with one of the tubesheets to provide an opening thereat of suflicient diameter to pass thetube fins when the tube was withdrawn. This construction isobjectionable because it introduces additional joints through whichleakage may occur and materially increases the cost of construction andmaintenance of apparatus in which it is used. For this reason it hasheretofore been considered impractical touse finned tubes in the aircooling sections of surface condensers and in certain other types ofcoolers.

It is the object of the present inventionto be novel and the invention,attention is now directed to the accompanying drawing, the descriptionthereof and the appended claims.

In the drawing, Fig. 1 is a side view, partly in section, of a finnedair-cooling tube embodying the invention and applied to a double tubesheet mounting for a surfa e air cooler Fig. 2 is a similar View slawing a modification applied to a single tube sheet mounting for asurface condenser, and-Fig. 3 is an end view, partly in'section and on agreatly reduced scale, .of a surface condenser provided with an aircooling section comprising a bank of tubes concurrent of air' to becooled is circulated and through which a stream of cooling water flowsfrom an inlet water box 6 to an outlet water box 7. ing to the usualpractice between the water boxes with its ends expanded tightly intotube shees 8 and 9 which form end heads for said water boxes.

The tube is provided with suitable cool ing fins 10, which in thepresent example are formed by a spiral metallic ribbon, preferably ofcopper, tightly wound edgewise thereon and soldered in place. The ribbonis shouldered along its inner edge tobprovide good thermal contactwith.the to e.

At one end, the tube is expanded or belled,

as indicated at 11, to increase its'external at the belled end as wellas the plain unbelled end, thus providing a very simple con-' structionand eliminating in the tube sheet through which it is designed to beinserted and withdrawn, the additional joints ordi narily provided by apacking ring about the tube end, together with the additionalcomplication andf possibilities of leakage which such packing ringintroduces. This advantage for the belled tube becomes of greatimportance when the large number of tubes used in any one piece ofcooling apparatus is considered.

It has been found that the belled tube can be made to the desireddiameter without internal metal stresses and without any sign ofdestructive action on the metal fibres.

Thus the belled tube is as sound as the straight tube now used insurface condensers The tube is mounted accordtance.

and surface air coolers and makes it possible to use cooling fins inpractically any place where a ain tube may be used and in many placeswhere a finned tube has heretofore been cdnsidered impracticahbecause ofthe additional packings required for one end of each tube. I

An example of this is the double tube sheet construction used in surfaceair coolers where the prevention of cooling water leakage .-i nto theair spaces is of impor- Tube sheets 8 and 9 are of the doubleconstruction providing a leakage space or chamber 12 into which leakageabout the tubeor tubes from the respective water boxes must pass beforereaching'the inner' tube sheet. Leakage flow from the chamber 12 iseasily detected and remedied before it becomes serious. The'faulty tubejoint or joints are located by removing the water box at the end whereleakage occurs and applying water pressure to the chamber 12 whileobserving the'tube ends. The tube or tubes about which leakage isindicated are then rerolled or expanded more tightly into the tubesheets.

Thus the double tube sheet provides a leakage chamber which separatesthe water boxes from direct leakage communication with the air spacesand facilitates testing for leaks.

It is therefore desirable to provide the double tube sheet in surfaceair coolers, but heretofore the use of finned tubes with the double tubesheet has not been considered to be practical because of the largenumber of additional joints introduced by the double sheets inconjunction with the removable packing rings required for the removal ofthe finned tubes. With the belled tube however, the use of finnedtubeswith double tube sheets is made practically possible and opens upfor new uses this desirable combination. Heretofore, with the use offinned tubes limited in practice tosingle tube sheets for thereasonabovestated, it was very diflicult to locate a faulty tube joint in asurface air cooler because it is not desirable to fill the shell or airspace thereof with water as it is in the case of a surface condenser.This generally necessitated repacking or rerolling all of the tubes inthe event of one or a few tube leakages.

Referring nowto Fig. 2. 13 is a cooling tube like that of Fig. 1,provided with similar cooling fins 14 and mounted at its ends in singletube sheets 15 and 16 of'a surface condenser. To provide. for thegreater expansion due to heating, the plain end of the tube in'tubesheet 16 .isnot expanded tightly into engagement therewith, but isprovided with a packing therein comprising a ring 17 surrounding thetube end with a tight sliding fit and threaded into a counterbored ecess18' in the tube sheet to compress packing materia1 19 contained in saidrecess tightly about the tube end. The latter extends into the recessthrough a central opening 20 at the rear thereof, which opening servesto center the tube end in the recess, The belled end of the tube'isexpanded into engagement with tube sheet 15, while the plan end is thuspermitted to move in the packing as the tube expands or contracts.

Midway between the tube ends a perforated supporting wall 21 is providedthrough which the tube passes. The wall forms a guide to prevent thetube fromdropping down, and becoming entangled with the fins of othertubes when being withdrawn or inserted and prevents the tube fromsagging in use.

The single tube sheets shown are used in surface condensers becauseleakage is not as serious as in a surface air cooler, such as a surfaceair cooler for an electric generator for example, and a leak may belocated without rerolling all of the tube ends, by

filling the shell or space surrounding theL tubes. with water andobserving the tube. ends.

Referring to Fig. 3, 22 is the shell of a surface condenser providedwith a top inlet 23, a vapor chamber 24 in which is located a bank ofwater tubes 25, and a hot well 26. Separated from the vapor chamber by adouble sloping wall 27 is an air cooler section 28 through'whichnoncondensable vapors and air pass from the vapor chamber to a sideoutlet 30. The air cooler section is provided with a bank of uniformlyspaced, finned water tubes 29. A gutter 31 is provided at the lower edgeof the sloping wall, from which gutter one or more gutter pipes 32 leaddownwardly toward the hot well. An opening 33 is provided in the lowerend of each gutter pipe and a double wall 27 provided with a heatinsulating space 34 serves to separate the vapor chamber and the aircooler section 28.

The water tubes 29 of the air cooling sections are constructed andmounted in accordance with the showing in Fig., 2, and because of thebelled end construction, permit the use of cooling fins withoutcomplicating the tube mounting to the extent of rendering the use offinned tubes impractr. cal in a condenser air cooling section as hasheretofore been the case with tubes of ordinary construction.

It. should be understood that the invention is not limited to the use ofcooling tubes with spiral fins, such as that shown, but may be carriedout in connection with other finned tube structuresin other types of aircooling apparatus.

\Vhat I claim as newand desire to secure .by Letters Patent of theUnited States, is:

1. A thin-walled tube having a main portion of uniform cross-section andan end portion of enlarged cross-section, and a spiral ribbonsurrounding said main portion of the tube in contact therewith,saidribbon being secured to the tube to form anhaving a shouldered inneredge secured to the tube and forming an air cooling fin therefor ofsmaller overall size than the belled end.

3. In combination, a thin-walled tube having an enlarged belled end,said tube being of uniform cross-section throughout the remainder of itslength, a spiral ribbon surrounding said tube, said ribbon being securedto the tube to form a thin air cooling fin-therefor of smaller overallsize than the belled end of the tube, spaced walls in which the tubeends are secured, and an intermediate supporting wall forthe tube havinga guide opening through which the tube passes, said guide opening andwall serving to reduce the sag of the tube between i-ts ends and tofacilitate the removal of said tube through -one of said spaced Walls. 7

In witness whereof, I have hereunto set my hand this 5th day of June,1925.

- ARTHUR R. SMITH.

